sink into something
to sit in a comfortable chair and let yourself fall back into it

[TahlilGaran] Dictionary of Contemporary English ▲

sit to be resting your weight on your bottom somewhere, or to move into this position:
He was sitting in front of the fire.
She sat on the bed and kicked off her shoes.
Who is the man sitting next to Karen?
sit down to sit on a chair, bed, floor etc after you have been standing:
I sat down on the sofa.
Come in and sit down.
be seated formal to be sitting in a particular chair or place:
John was seated on my left.
There was a man seated behind the desk.
take a seat to sit – used especially when asking someone to sit down:
Please take a seat – she will be with you in a minute.
Would the audience please take their seats – the show will begin in five minutes.
sink into something to sit in a comfortable chair and let yourself fall back into it:
We switched on the TV and sank into our armchairs.
lounge to sit in a very comfortable relaxed way:
They lounged around all day by the pool.
perch to sit on the edge of something:
He perched on the arm of the sofa.
My sister was perched (=was sitting) on a high stool.
be slumped to be sitting while leaning against something, especially because you are injured, drunk, or asleep:
They found him slumped against the steering wheel.
squat to sit with your knees bent under you, your bottom just off the ground, balancing on your feet:
A little boy was squatting at the edge of the pool.

[TahlilGaran] English Thesaurus ▲